Over six decades ago, an analog television standard named after the governing body that developed it—the National Television System(s) Committee (NTSC)—became the standard for television signal transmission in the United States. The NTSC standard was later adopted by other countries including Japan and most of North and South America. The NTSC standard is sometimes criticized for its poor color balance and low quality image. Nonetheless, NTSC has flourished and is still in use today. Many attribute the success and ubiquity of NTSC to its wide-ranging compatibility with television and broadcast devices and its forward and backward compatibility among the various versions of the NTSC standard itself. However, it soon became apparent that a new standard was needed to replace the NTSC standard and to incorporate emerging digital technologies. Established in 1982, the Advanced Television System(s) Committee (ATSC) developed a digital television standard. The digital television standard was named after the governing body—ATSC. The ATSC standard supports a 16:9 ratio, up to 1920 pixels wide, and up to 1080 lines of resolution—more than six times the display resolution of the NTSC (analog) standard. The ATSC standard is intended to replace the NTSC standard.
Notwithstanding the enhanced image quality provided by the ATSC standard, a large portion of the general population continue to own and use television sets that lack support for the new ATSC standard. This presents a dilemma to broadcast stations. Replacing an entire broadcast station's infrastructure with equipment capable of supporting the ATSC standard is costly. Such an approach may offer a low return on investment considering that much of the population have no way of watching ATSC signals on their television sets. Alternatively, broadcast stations may opt to maintain video content in NTSC form, and up-convert the NTSC material into an ATSC signal as a final step in the transmission of the signal. This allows an incremental investment or partial replacement of the infrastructure because less equipment is required. This approach also allows broadcast stations to continue to provide NTSC signals to those customers who may still demand it. Thus, many broadcast stations use up-converters as part of their infrastructure to enable transmission of legacy standard NTSC material to ATSC signals.
Some broadcasters do not correctly handle the up-conversion of NTSC material to ATSC signals. The NSTC standard includes a provision for a vertical blanking interval (VBI). The vertical blanking interval is the time period required for a scanning electron beam to return from the last line of a given video field, to the first line of a next video field. During this time period, 22 horizontal lines known as VBI lines are displayed to the screen. To avoid adverse effects to the image quality of an NTSC video display, VBI lines are purposely weak and detectable only by circuitry designed to decode information stored in the VBI lines such as close caption (CC) and v-chip data. ATSC digital television signals should not include VBI lines. An up-conversion of an NTSC signal which contains VBI lines to an ATSC signal should crop the VBI lines to avoid annoying flashing in the ATSC signal. In some cases, broadcasters properly up-convert the signals resulting in the transmitted image consisting only of the active video. In other cases, broadcasters improperly up-convert the signals resulting in one or two lines of the VBI being shown in the display area creating an annoying flashing as the close caption (CC)/v-chip data is broadcast. In the most extreme case, no VBI cropping occurs, which results in all of the lines of VBI being displayed together with the active video.
There are also numerous channels that have shows of various aspect ratios. It would be advantageous to have an improved video system and method for automatic aspect ration (size and position) adjustment according to the incoming stream. Televisions and other display devices lack the ability to detect the size and position of incoming video and adjust the scale mode to match. Users of these types of display devices are often un-savvy with technology in general, and particularly with often complex and sometimes confusing television aspect ratios, formats, and scale modes. Typically, a user would prefer that the TV or system handle the complexity on their behalf in an automated fashion. Other types of users may prefer the latitude of manually refining the characteristics of the display device by specifically choosing a particular display mode. Even the more sophisticated users, however, prefer to have an intuitive on screen display (OSD)—one with clear options that are easily understood and properly labeled. Display devices may have multiple media input sources. This may further complicate the configuration of the scale mode and other characteristics of a particular input source or channel.
Accordingly, a need remains for a video system to properly output video data to a display device. And a need remains for a video system with an automatic detection feature that automatically detects the size and position of an input stream and adjusts the scale mode to match. There also is a need for an intuitive on screen display (OSD).